Device including light emitting diode as light sensor and light source

ABSTRACT

A battery operated controller for a door operator includes a keypad backlit by a light emitting diode operably connected to a microcontroller which also controls operation of the controller. The microcontroller periodically measures ambient light as sensed by the light emitting diode and when a voltage level related to a predetermined light intensity decreases below a predetermined level the light emitting diode is energized to provide backlighting for the controller keypad. The intensity of backlighting may be varied in accordance with the amount of ambient light illuminating the keypad and above a certain intensity of ambient light the light emitting diode is de-energized to conserve battery power.

BACKGROUND

Certain battery operated devices utilize light emitting diodes (LEDs) aslight sources. For example, garage door opener controller devices,sometimes referred to as consoles, are often provided with backlitkeypads and operating switches so that the openers may be actuated underpoor or nonexistent ambient light. However, conventional garage dooropener consoles are characterized by LED light sources which are always“on” at a constant intensity and thus comprise a drain on battery powerwhich shortens battery life unnecessarily. Thus, it would beadvantageous if battery operated devices, such as garage door openerconsoles, were provided which reduce consumption of battery power duringdaylight hours when artificial and power consuming light sources are notrequired. It is to these ends that the present invention has beendeveloped.

SUMMARY OF THE INVENTION

The present invention provides a battery powered device, such as agarage door opener controller, which utilizes at least one lightemitting diode (LED) as a light source and a light sensor for adjustingthe intensity of the light source as required by ambient lightconditions.

In accordance with one aspect of the present invention, a garage dooropener controller or console is provided with circuitry which includes akeypad backlight source comprising an LED, which LED is connected to acontrol circuit for sensing ambient light and for adjusting theintensity of light emitted by the LED, thus conserving battery powerduring conditions of adequate ambient light.

In accordance with another aspect of the invention, a device is providedwhich includes a keypad and a source of lighting for such keypadcomprising an LED. The LED is connected to a microcontroller, sensesambient light and causes the microcontroller to adjust an electricalsignal imposed on the LED to adjust the intensity of lighting of thekeypad in accordance with ambient light conditions.

Still further, the present invention provides a garage door openercontroller device, such as a wall console, which is battery powered,includes a keypad for entering a personal identification or access codeand/or a door open-close button type switch actuator and an LEDbacklight source, which backlight source also senses ambient light and,together with a microcontroller, operates to adjust the voltage imposedon the LED in the light source operating mode to conserve battery powerduring periods when ambient light is adequate for viewing the keypadand/or door control switch actuator.

The present invention is advantageous in that the cost of a dedicatedphotosensor and associated circuitry is eliminated thus providing forthe reduction in space required by such circuitry and costs associatedtherewith. Improved battery life for devices according to the presentinvention is provided and the circuitry of the invention provides forefficient utilization of microcontroller or integrated circuit deviceswhere only one input/output (I/O) pin or terminal is used for sensingambient light and for providing backlighting versus the use of pluraldedicated pins for each function in prior art devices. Thus, by reducingthe required microcontroller pin count, the cost of the controlcircuitry is reduced. Since an LED cannot operate in both light sensingand light emitting mode simultaneously, a microcontroller connected tothe LED may set a digital input/output line to be an analog input. Theambient light level is sensed by the LED operating in a photovoltaicmode and the microcontroller converts an analog input to digital formand determines if backlighting should be “on” or “off” and at a suitablelevel of modulation in the “on” mode. Further, in accordance with theinvention, a microcontroller is provided which is operated in a mannerwhich sets the digital input/output line as a digital output and turnsthe LED on or off or modulates the intensity of light emitted thereby.Moreover, the microcontroller may be configured such that the stepsdescribed above may be repeated as often as appropriate for a particularapplication.

Those skilled in the art will appreciate that the invention may be usedfor battery operated devices having other types of displays thatincorporate backlighting including wireless-keyless entry controldevices, and portable/hand held devices including test equipment andcommunication devices.

Those skilled in the art will further appreciate the advantages andsuperior features of the invention upon reading the detailed descriptionwhich follows in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a device in accordance with theinvention comprising a battery powered wall console controller unit fora garage door operator;

FIG. 2 is a detail section view taken generally along the line 2—2 ofFIG. 1;

FIG. 3 is a circuit diagram of certain circuit elements for the consolecontroller unit shown in FIGS. 1 and 2; and

FIG. 4 is a flow diagram showing the steps executed by control circuitryfor adjusting the intensity of light emitted by an LED light source forthe controller unit.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

In the description which follows like parts are marked throughout thespecification and drawing with the same reference numerals,respectively. The drawing figures are not necessarily to scale andcertain features may be shown exaggerated in scale or in somewhatgeneralized or schematic form in the interest of clarity andconciseness.

Referring to FIG. 1, there is illustrated a device in accordance withthe invention comprising a wall console type controller unit 10 forremote control of a garage door operator, not shown. The consolecontroller 10 is typically of a type which may be mounted on an exteriorwall of a residential or commercial building for operating a door, suchas an upward acting garage door, by entering a multi-digit code by wayof a keypad 12 including alphanumeric push button switch actuators 14and an operate or open/close switch actuator 16, for example. The dooroperator controller or console 10 may be programmable for adding ordeleting selected multi-digit codes associated with persons authorizedto control the door operator. The controller 10 is characterized by agenerally rectangular housing 11 mountable on a wall, not shown. Housing11 includes a separable cover member 13, FIG. 1. A battery compartmentfor supplying electrical power to the controller is accessed through aremovable cover 18 and said compartment contains a battery 18 a.

Referring also to FIG. 2, the alphanumeric keypad switch actuators 14and the open/close switch actuator 16 are of a type wherein a somewhatflexible light transmitting molded polymer pad part 20 forms the buttontype actuators 14 and 16 for respective switches whereby the buttonactuators 14 and 16 project through suitable openings 15 and 17,respectively, formed in cover part 13. At least one light emitting diode22 is mounted within the housing 11, as shown in FIG. 2, and projectslight onto the light transmitting pad 20 for transmission to the buttonactuators 14 and 16 whereby the respective button actuators are suitablyilluminated for viewing in low ambient light conditions. LED 22 isexemplary and more than one LED may be used to backlight the pad part 20and the respective button type actuators 14 and 16.

In many applications LEDs are so-called forwardly biased electricallyand are designed to operate at an electrical current flowingtherethrough that provides suitable brightness to illuminate objects,such as the switch pad part 20, for example. Under such conditions LEDsare referred to as operating in the light emitting mode. However, LEDscan be used as photosensors when not forwardly biased. For example, whenlight strikes an LED, a voltage is produced across the LED in theso-called photovoltaic mode and the voltage increases as the intensityof light striking the LED increases. Accordingly, ambient light is alsotransmitted from the button actuators 14 and/or 16 to the cavity 21,FIG. 2, in which the LED 22 is projecting and this ambient light issensed by the LED. Alternatively, a suitable opening 25, FIGS. 1 and 2,may be provided in the cover 13 to provide a more direct path for lightonto and through the pad part 20 for sensing by the LED 22.

LEDs normally cannot operate in the light emitting and light sensingmode simultaneously. Accordingly, one preferred mode of operation for anLED which is both light emitting and light sensing is to connect the LEDoperably to a circuit, such as a microcontroller, in such a way thatambient light is sensed by the LED operating in the photo-voltaic modewhereby the aforementioned microcontroller converts an analog inputsignal from the LED to digital form and determines if the backlightprovided by the LED should be on or off, or determines the appropriatelevel of light to be emitted by the LED.

Referring now to FIG. 3, there is illustrated a diagram for a preferredcircuit for the operator controller 10. Circuitry represented by thediagram of FIG. 3 is disposed within the housing 11 and suitablyconnected to a source of electrical power comprising battery 18 a,FIG. 1. A microcontroller U1, FIG. 3, is operable to output apredetermined voltage on output terminal RC0 which forward biases LED 22energizing same and providing backlighting for the switch pad part 20and the individual switch actuators 14 and 16. This backlighting, ofcourse, draws current from battery 18 a and reduces the operating lifeof same. However, when the circuit of FIG. 3 is first energized by thebattery 18 a, the microcontroller U1 sets an output on terminal RC0 to ahigh impedance state. Terminal RA0 is then configured as an analog inputand the microcontroller performs an analog to digital conversion onterminal RA0 measuring the voltage across the LED 22. Light striking thepad part 20 via the actuators 14 or 16 or via the opening 25 istransmitted to the LED 22 thus creating a voltage developed as aconsequence of the intensity of such light. Microcontroller U1 may beprogrammed such that, at a preset voltage level emitted by the LED 22corresponding to adequate ambient light, the microcontroller U1 will notenergize the LED 22 in the lighting mode. Accordingly, the LED 22 isenergized to backlight the pad part 20 only if ambient light conditionsare such that it is necessary to have backlighting of the pad part.

The circuit diagram of FIG. 3 also depicts an array of switchesassociated with each of the switch actuators 14 and 16, these switchesbeing indicated by reference numerals S1 through S13 and wherein switchS1 is a programming switch which may be actuated by an actuator 14 a,FIG. 1. The switch array illustrated in the circuit diagram of FIG. 3interfaces with the microcontroller U1 via the connector tabs indicatedfor terminals RC3, RC4, RC5, RA1, RA1, RA3 and RA4. The circuit diagramof FIG. 3 also illustrates a power supply circuit including a regulatorcircuit U2. When any switch S1 through S13 is actuated, a ground path iscreated for the enable output of the regulator U2 which turns on andsupplies power to the microcontroller U1. Microcontroller U1 thenexecutes programmed instructions and outputs a voltage that energizestransistor Q4, which, in turn, maintains regulator U2 in an on mode.Microcontroller U1 is also operably connected to a radio frequency (RF)circuit, as shown, for transmitting door open/close signals to a dooroperator, not shown.

An indicator LED DS1 flashes at various rates for user feedback. Forexample, the microcontroller U1 monitors the switches S1 through S13 ofthe controller and when a key is pressed, the microcontroller viatransistor Q2 flashes LED DS1 to give the user positive feedback thatthe switch has been pressed. LED DS1 is also depicted by the referencenumeral 14 b in FIG. 1 which may be a light transmitting portion of padpart 20 projecting through a suitable opening in cover 13, asillustrated.

The microcontroller U1 may be programmed to periodically test ambientlight conditions by de-energizing LED 22, measuring ambient light andthen resuming energization of LED 22 at a voltage commensurate withambient light conditions which may warrant backlighting the pad part 20and the switch actuators 14, 14 a and 16.

Referring briefly to FIG. 4, there is illustrated a flow diagram ofsteps executed by the microcontroller U1 to sense ambient light and setthe voltage applied to the LED 22. As shown in FIG. 4, power on to themicrocontroller U1 is indicated at step 40. Step 42 indicates settingthe LED input/output terminal for analog input and step 44 indicatesreading the voltage output of the LED via an analog to digitalconversion and which is indicative of the intensity of ambient lightfalling on the controller unit 10.

As the routine proceeds to step 46, the voltage level read from the LEDis compared with a preset low ambient light voltage signal and if thevoltage is less than the preset value the routine proceeds to set theLED input/output terminal for a digital output signal at step 48 whichthen results in energizing the LED to backlight the switch actuators 14and 16 at a predetermined intensity as determined by the comparison ofthe voltage level read on the LED I/O line. Step 50 indicates themicrocontroller U1 actually energizing the LED and step 52 indicatescontinuation of the normal routine programmed into the microcontrollerU1 which may, periodically, call for repeating the steps shown in FIG.4. As indicated in FIG. 4, if the voltage level read on the LED I/O lineor pin is not less than the preset level the program is set for the LEDI/O line to provide a digital input signal. However, the LED 22 is notenergized since ambient light is indicated to be sufficient, asindicated at step 49 in FIG. 4. Thus, electrical current consumption isminimized and battery life is improved since the switch actuators 14 and16 are not backlit when not required to be.

Table 1 is a list of components found in the circuit diagram of FIG. 3and indicating general operating parameters and a typical commercialsource, respectively.

TABLE 1 Reference Example of Designator Description Commercial Source CxIndustry Standard Capacitors Murata/AVX Rx Industry Standard ResistorsSEI Dx Industry Standard Diodes Rohm D1 Zener Diode Vishay DS1 LightEmitting Diode Kingbright Corp. DS4 Light Emitting Diode KingbrightCorp. Qx Industry Standard Transistor Rohm Module Sx Carbon Pill SwitchITT U1 Microcontroller Microchip #PIC16F676 U2 Low Dropout Voltage TexasInstruments Regulator #TPS76950

Although a preferred embodiment of the invention has been described andshown in detail, those skilled in the art will recognize that variousmodifications and substitutions may be made without departing from thescope and spirit of the appended claims.

1. A battery operated controller for a door operator comprising: a light transmitting switch actuator pad including plural switch actuators and operable to transmit visible light from a light source comprising a light emitting diode; said light emitting diode is positioned such as to backlight said switch actuator pad and to sense ambient light transmitted directly from said switch actuator pad to said light emitting diode; a circuit including said light emitting diode for generating visible light to illuminate said switch actuator pad; and a microcontroller operably connected to said circuit including said light emitting diode for sensing ambient light on said switch actuator pad and for energizing said light emitting diode when said ambient light is less than a predetermined intensity, said microcontroller is programmed to periodically deenergize said light emitting diode, measure the intensity of ambient light transmitted by said switch actuator pad to said light emitting diode and energize said light emitting diode if the measured intensity is less than a predetermined amount, said microcontroller further being operable for converting a voltage signal from said light emitting diode to a digital signal, comparing said digital signal to a preset signal corresponding to a level of ambient light intensity and energizing said light emitting diode at a voltage related to the intensity of ambient light and producing an intensity of light emitted by said light emitting diode required to compensate for insufficient ambient light.
 2. The controller set forth in claim 1 including: plural switches associated with said switch actuators, respectively, and operably connected to said microcontroller by way of a regulator circuit for enabling said microcontroller in response to actuation of any of said switches.
 3. The controller set forth in claim 2 including: a visual indicator operably connected to said microcontroller and responsive to an output signal from said microcontroller which is responsive to actuation of one or more of said switches to provide a visual user feedback signal.
 4. The controller set forth in claim 3 including: a switch operably connected to said microcontroller and said indicator and responsive to a signal from said microcontroller for energizing said indicator.
 5. The controller set forth in claim 2 including: a switch operably connected to said microcontroller and to said regulator circuit and operable to maintain said regulator circuit in a condition to enable said microcontroller.
 6. The controller set forth in claim 2 including: a radio frequency transmitter operably connected to said microcontroller and responsive to actuation of selected ones of said switches to transmit a signal to a door operator.
 7. A battery operated controller for a door operator comprising: a light transmitting switch actuator pad including plural switch actuators and operable to transmit visible light from a light source comprising a light emitting diode; said light emitting diode is positioned such as to backlight said switch actuator pad and to sense ambient light transmitted directly from said switch actuator pad to said light emitting diode; a circuit including said light emitting diode for generating visible light to illuminate said switch actuator pad; a microcontroller operably connected to said circuit including said light emitting diode for sensing ambient light on said switch actuator pad and for energizing said light emitting diode when said ambient light is less than a predetermined intensity, said microcontroller is programmed to periodically deenergize said light emitting diode, measure the intensity of ambient light transmitted by said switch actuator pad to said light emitting diode and energize said light emitting diode if the measured intensity is less than a predetermined amount, said microcontroller further being operable for comparing a signal from said light emitting diode to a preset signal corresponding to a level of ambient light intensity and energizing said light emitting diode at a voltage related to the intensity of ambient light and producing an intensity of light emitted by said light emitting diode required to compensate for insufficient ambient light; plural switches associated with said switch actuators, respectively; and a regulator circuit operably connected to said switches and said microcontroller for enabling said microcontroller in response to actuation of any of said switches.
 8. The controller set forth in claim 7 including: a switch operably connected to said microcontroller and to said regulator circuit and operable to maintain said regulator circuit in a condition to enable said microcontroller.
 9. The controller set forth in claim 7 including: a radio frequency transmitter operably connected to said microcontroller and responsive to actuation of selected ones of said switches to transmit a signal to a door operator.
 10. A battery operated controller for a door operator comprising: a light transmitting switch actuator pad including plural switch actuators and operable to transmit visible light from a light source comprising a light emitting diode; said light emitting diode is positioned such as to backlight said switch actuator pad and to sense ambient light transmitted directly from said switch actuator pad to said light emitting diode; a circuit including said light emitting diode for generating visible light to illuminate said switch actuator pad; a microcontroller operably connected to said circuit including said light emitting diode for sensing ambient light on said switch actuator pad and for energizing said light emitting diode when said ambient light is less than a predetermined intensity, said microcontroller is programmed to periodically deenergize said light emitting diode, measure the intensity of ambient light transmitted by said switch actuator pad to said light emitting diode and energize said light emitting diode if the measured intensity is less than a predetermined amount, said microcontroller further being operable for comparing a signal from said light emitting diode to a preset signal corresponding to a level of ambient light intensity and energizing said light emitting diode at a voltage related to the intensity of ambient light and producing an intensity of light emitted by said light emitting diode required to compensate for insufficient ambient light; and a visual indicator operably connected to said microcontroller and responsive to an output signal from said microcontroller which is responsive to actuation of one or more switches associated with said switch actuators, respectively, to provide a visual user feedback signal by way of said switch actuator pad.
 11. The controller set forth in claim 10 including: a switch operably connected to said microcontroller and to a regulator circuit and operable to maintain said regulator circuit in a condition to enable said microcontroller.
 12. The controller set forth in claim 11 including: a radio frequency transmitter operably connected to said microcontroller and responsive to actuation of selected ones of said switches to transmit a signal to a door operator. 